Duplicating machine



- 1931- F. CHESLEY ,DUPLICATING MACHINE Filed Sept. 4, 1929 mveu'ron I ATTORNEY:

' Patented Dec. 8,. 1931 v rum; mm, or pours'vmw, mmucxr, assrenon u. coorna or are-arm 1 hurt-warms mm Application filed September 4, 1929. Serial I'm $0,351.

This invention relates to duplicating niachines, and is particularly directed to a machine in which a minimum sized conveniently applied printing blanket or flexible sheet I may housed, and to the features of the machine relative to conven'ient'and rapid application and tensioning of the printing blanket over a platen.

The present commercial type duplicating 1o machines utilize a roll or continuous printing blanket or hectograph sheet which is reset or adjusted over the surface of the platen for a new printing operation after the required number of copies or transfers have been made from an impression 'or print placed on the special surface of the rinting blanket. This form of blanket or ectograph sheet now in use is composed of a layer of gelatin treated with glycerine placed on a backing to of cloth, the layer holding the printing, writing, sketching, etc., on its surface for a period of time suitable for printing a number of copies. The printing or writing, after the pawage of considerable time, becomes inefi'ec- 2 tive for contact transfer, since it is absorbed 1 or penetrates into the layer. When the tion of the sheet is again usable.

The machine now commonly in use embodies the printing sheet roll for the purpose of changing the portion of the roll over the platen when it is desired to closely succeed printing operations on the same machine. This roller blanket is'of considerable length and therefore quite expensive. Frequently,

it is damaged or unequally worn and=must be discarded entirely.

In the present invention, printing sheets of short length are used, just sufiicient to cover the platen, which sheets drill quickly attached and stretched over the s ace of the platen by devices at the respective ends of the table holding the laten. After a printing 0 eration, each s eet is removed without di culty and a fresh printing sheet applied.

It is, herefore, an object of th s invention to provide a duplicating machine of simple form, to which individual printing or heetograph shwts for each operation ma'y be quickly applied and removed. Proti sio n is thus made for a 'cheaplymanu'facturedmachlne economically maintained and conveniently operated. I L

-It is another object of, this invention to provide a duplicating machine incorporating eflicient attaching means'ortelisio'ning devices for stretching a printing sheet over the platen, which means are rapidly and easily manipulated and thejsheet accurately snapped into position. These, mounting devices on the machine are intended'for mounting. any type of sheet and for mounting either rotatable or stationary spindles... y

It is another objectof-tliis invention to provide guiding facilitie'sion the machine aiding the operator in uniformly placing the successive sheets, to be printed,on theprinting sheet for transfer therefrom.

Other obgects relate to the general construction o a simple, portable duplicating machine, which objects and advantages will be more fully set forth in the description of the accompanying drawings, in which:

Figure 1 is a general perspective view of the lahket in position. I. Figure 2 is a transverse sectional View illustrating the ,table construction and the relation of the guide to the printing sheet and platen.

Figure 3 is a sectional view taken on line .dl't' hinh'- 't'htproper time has elapsed, the particular por- 3 ma mg mac 6 S owmg l mg 8 ee 3-3, Figure 2, illustrating the sheet attachmounted on each end of the table, and a guide 8 extending longitudinally on t e top surface of.the table along the side of t e platen. A rinting-blanket 9 is disposed ,over the surace of the platen and secured at its respectensioning of the sheet over the platen.

Referring specifically to the details of the drawings, the table 5 provides a leg at -each corner thereof, a rubber button or cushion 11 being secured to the underside of each leg for preventing contact of the metal of the table with the surface upon which the device is placed. The table presents a smooth top u on which a layer of felt, constituting the p aten 6, is secured. Each tensioning device comprises a bar 13 having upwardly extending hooks 14 formed integrally therew th at'each end, thesehooks being outwardly d1sposed relative to the table.

The bar 13 is mounted transversely across the end of the table, well down below the surface thereof, by means of studs 15, one secured in each end of the bar, these studs extending through the end wall of the table and having threaded ends upon each of which a nut 16 and washer 17 are secured. A

tapered coil compression spring 18, surround-- ing each stud, is disposed between the bar and the wall of the table. The bores 19 through which the studs extend are of greater diameter than the studs, permitting rocking or canting of the studs relative thereto. This rocking takes ,place between the nuts and the washers and is a vertical movement permitting the hooks to be pressed inwardly against spring pressure.

The printing blanket 9 is a standardized product embodying a layer of gelatin treated with glycerine disposed on a fabric backing. A hem 20'is provided at each end of the blanket being formed by stitching a strip of fabric to the margin of the blanket, the strip overlapped upon the respective sides of the blanket and providing a clearance between the edge of the blanket and the fold of the strip, through which clearance or hem a rod- 21 is inserted, this rod or spindle extending from each end of the hem as at 22.

The hooks of the tensioning devices are sutficiently spaced apart to permit the width of the blanket and length ofhem to be disposed therebetween and the, spindles or rods to engage the hooks. The blanket is placed in position by booking the spindles at one end' thereof in the respective hooks, drawing the blanket tautly across the surface of the platen and forcing the tensioning device at the opposite 'end of the machine inwardly, tipping the books with the thumb of each hand, while the forefinger of eachhand en-- gages the spindles and forces them over the 00k edges, as shown in Figure 4.

The spindles are spaced apart a suitable distance for causing a slight tipping of the tensioning devices when the blanket is in position, this lplacing the blanket under spring tension at al times, whereby it is tautly engaged over the surface of the platen, the ositionof the hooks below the surface 0 the table aiding in the proper disposition of the blanket on the platen.

The guide 8 is of angle iron form and extendsapproximately the length of the platen, being secured to the surface of the table along the edge of the platen with the angle inwardly facing. One end of the angle iron guide strip is provided with a transverse flange 23, providing a stop at that end of the guide, and the other end of the angle has the upstanding flange bent downwardly as at 24 to provide a channel for accurate in-. sertion of the sheets'to be printed and for preventin rising of the sheet margin relative to the gui e.

In operation, a sheet or printing blanket is placed in position as above described. The drawing or printing to be copied is drawn upon an original, using the proper ink or writing instrumentality, which will be readily transferable to the surface of the blanket, placing the original sheet inscribed face down upon the blanket, rubbing'or rolling over the sheet, which causes adherence to the blanket. The original is then stripped from the. blanket and the writing or drawing has been transferred to the glycerine surface. Thereupon, sheets are successively placed against the surface of the printing sheet against the guide edge and against its sto'p end until the required number of copies have been made.

Inasmuch as it will require a considerable number of hours for the data on the printing blanket to penetrate the layer of compound, the blanket may be removed and replaced by a fresh blanket. Successive blankets may be, used and in the end the first used blankets will be reconditioned by the absorption of the printing into the layer.

Having described my invention, I claim:

'1. In a duplicating machine, a table, a tensioning device at each end of the table, said tensioning devices having outwardly facing hooks disposed below the surface of the table, springs for urging said hooks outwardly, and a printing blanket disposed upon the surface of the table, said blanket having spindles attached across its ends engageable within the respective hooks when the hooks are forced inwardly against said springs, where- 'by the blanket is placed under tension across the hooks are forced inwardly against the pressure of said springs, whereby the blanket is placed under tension across the surface of the table.

3. A duplicating machine, comprising, a 7 table, a platen on said table, a tensioning device at each end of the table, tensionin device, comprising, a bar providing outwar 1 1y disposed hooks at the respective corners of the table, studs extending from said bar through the table, compresslon springs between the bar and the wall of the table, means for mounting the studs relativeto the table,

the studs traversing bores of greater diameter than the studs for permitting tilting of the studs relative 'to the bores, a printing blanket having hems at the ends thereof, an

rods traversing said hems and having their ends extending beyond the respective ends of the hems, said extending ends engageable in said hooks upon tilting of the hooks and compression of the springs.

4. A duplicating machine, comprising, a table, a tensioning device at each end of the table, each tensioning device, comprising,

outwardly disposed hooks at the respective corners of the table, studs extending from said hooks through the table, compression springs between the hooks and the wall of the table, means for securing the studs relative to the table, the studs traversing bores of greater diameter than the diameter of the studs for permitting tilting of the studs relative to the bores, a printing blanket, and rods secured at the ends of the blanket and having their ends extending beyond the respective said edges of the blanket, said extending ends engageable in said hooks upon tilting of the hooks and compressionof the 5. A duplicating machine, comprising, a table, a platen on said table, hooks at the r spective corners oi the table, studs extending from said hooks through the table, coil compression springs between the hooks and the wall of the table, and means for securing the studs relative to the table, the studstraversing bores of greater diameter than the studs for tilting of the studs relative to the bores, and a printing blanket having rods my name.

extending from its corners, said rods engageable in said hooks upon tilting of the hooks and compression of the springs.

In witness whereof, I hereunto subscribe m CHESLEY. 

